GB706965A - Improvements in or relating to vapour generating and superheating units - Google Patents

Abstract

706,965. Water-tube steam boilers; superheaters and reheaters. BABCOCK & WILCOX, Ltd. Aug. 22, 1952 [Aug. 23. 1951], No. 21174/52. Classes 123(2) and 123(3) A steam boiler comprises a furnace 10 which is lined with steam-generating tubes such as 16, 18, 24 and is fired by three superposed rows cf burners 46, 47, 48 and' the gases from which flow through. a secondary superheater 64 to the inlets 66, 68 respectively of a gas by-pass 70 and three parallel gas passes 72, 73, 74, the later being arranged side-by-side at the rear of the said by-pass 70. The gas passes 72, 74 are disposed symmetrical with respect to the pass 73 and the centre line of the boiler and each houses one-half 98 ...102 of a primary superheater, whereas the pass 73 houses a reheater, not shown, and the by-pass 70 an economizer 82...84. The outlet of each individual gas pass 72...74 is fitted with a series of control dampers 140, and similarly the outlet of the by-pass 70 has independently operable dampers 142, all these outlets opening into a common breeching 150 which leads to a flue and is provided with a return branch 160, having a fan 162 and damper 168, for recirculation of some of the gases through the boiler. The superheater and reheater are adapted to give the desired steam temperatures at an intermediate control point in the load range of the boiler; these temperatures are maintained, at loads below the predetermined control point, by a controlled recirculation of gases through the return branch 160 together with operation of the three series of dampers 142, and, at loads above, by operation of the by-pass dampers 140 and the said dampers 142. Temperature indicators 119, 159 and 199 are fitted. respectively in the superheated steam outlet pipe 118, the reheater outlet 157, and the outlet headers 93 of the primary superheater.